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The emerging polyethylenimine (PEI)-functionalized solid adsorbents have witnessed significant development in the implementation of CO2 capture and separation because of their decent adsorption capacity, recyclability, and scalability. As an indispensable substrate, the importance of selecting porous solid supports in PEI functionalization for CO2 adsorption was commonly overlooked in many previous investigations, which instead emphasized screening amine types or developing complex porous materials. To this end, we scrutinized the critical role of different commercial porous supports (silica, alumina, activated carbon, and polymeric resins) in PEI impregnation in this study, taking into account multiple perspectives. Hereinto, the present results identified that abundant larger pore structures and surface functional groups were conducive to loading a considerable amount of PEI molecules. Various supports after PEI functionalization had great differences in adsorption capacities, amine efficiencies, and the corresponding optimal temperatures. In addition, more attention was paid to the role of porous supports in long-term stability during the consecutive adsorption-regeneration cycles, while N2 and CO2 purging as regeneration strategies, respectively. Especially, CO2-induced degradation due to urea species formation was specifically recognized in a SiO2-based adsorbent, which would induce serious concerns in CO2 cyclic capture. On the other side, we also confirmed that adopting conventional porous supports, for example, HP20, could achieve superior adsorption performance (above 4 mmol CO2/g) and cyclic stability (around 1% loss after 30 cycles) rather than the ones synthesized through complex approaches, which ensured the availability and scalability of PEI-functionalized CO2 adsorbents.

As a narrow band gap semiconductor, wurtzite β-CuGaO2 has drawn increasing attention in the area of solar energy. Although β-CuGaO2 has been theoretically predicted to possess ferroelectric polarization, its experimental ferroelectric characterization and practical applications have not yet been presented. Herein, firstly we experimentally confirmed its ferroelectric property via hysteresis loop measurement. The result showed a remanent polarization value of 10.20 μC·cm−2 with low coercive electric field of 6.45 kV·cm−1 at 20 Hz at room temperature, while the leakage current density (J) value was found to be 1.188 A·cm−2, which suggested the property of a larger remnant polarization with low coercive electric field than current value if the compactness was strengthened. Then, the synergistic effect of ferroelectric and semiconductor was comparatively highlighted by the experiment of pollutant degradation. Within 30 min, methyl orange degradation efficiency had reached 30.73% only in the case of spontaneous polarization (electricity), while it could reach 67.58% under the effect of pre-polarized β-CuGaO2 powder due to the modulating orientation of ferroelectric domains. Once irradiated (light), it was up to 92% within 30 min; in comparison, it merely took 16 min up to 92% degradation efficiency under both illumination and pre-polarization. If without illumination, it was 92.01% with 30 min in the condition of ordinary ultrasonic vibration (force) while under both illumination and ultrasonic vibration, only 11 min was spent to reach 92.79% degradation efficiency. All these results felicitously indicated that β-CuGaO2 had fascinating potential in energy harvesting (such as electricity, light, force) and transformation as wastewater environment remediation catalyst.

The development of multiphase composite electrocatalysts plays a key role in achieving the efficient and durable operation of intermediate-temperature solid oxide fuel cells (IT-SOFCs). Herein, a self-assembled nanocomposite is developed as the oxygen reduction reaction (ORR) catalyst for IT-SOFCs through a coprecipitation method. The nanocomposite is composed of a doped (Mn0.6Mg0.4)0.8Sc0.2Co2O4 (MMSCO) spinel oxide (84 wt %), an orthorhombic perovskite phase (11.3 wt %, the spontaneous combination of PrO2 additives and spinel), and a minor Sc2O3 phase (4.7 wt %). The surface of the (Mn0.6Mg0.4)0.8Sc0.2Co2O4 phase is activated by the self-assembled nanocoating with many heterogeneous interfaces. Thence, the ORR kinetics is obviously accelerated and an area-specific resistance (ASR) of ∼0.11 Ω cm2 is obtained at 750 °C. Moreover, a single cell with the cathode shows a peak power density (PPD) of 1144.1 mW cm-2 at 750 °C, much higher than that of the cell with the MnCo2O4 cathode (456.2 mW cm-2). An enhanced stability of ∼120 h (0.8 A cm-2, 750 °C) is also achieved, related to the reduced thermal expansion coefficient (13.9 × 10-6 K-1). The improvement in ORR kinetics and stability can be attributed to the refinement of grains, the formation of heterointerfaces, and the enhancement of mechanical compatibility.

Because the valence state of metal with variable valences is sensitive to oxidation atmosphere, it is difficult to fabricate single-phased metal oxide with intermediate valence by vapor or vacuum deposition. In this work, the copper valence state in oxides was controlled by introducing a nitrogen flow into the sputtering chamber. The surface chemical potential of oxygen can be efficiently tuned through adsorption competition on the growth surface. The transition process from CuO–Cu2O mixture to single Cu2O was observed with increasing the nitrogen flow rate. For the single-phased Cu2O, the hole concentration was tuned in a range of 2.6 × 1017 to 1.1 × 1018 cm−3.

Pyrolysis characteristics of chemical extraction microalgae residue in the presence and absence of catalysts (KCl, KOH, K2CO3, Al2O3, CaO, MgO and pyrolysis char of microalgae residue) were evaluated using a thermal analyzer and a tube furnace reactor. These catalysts can effectively improve the oil yield during microalgae residue pyrolysis. The order of the strength on increasing the oil yield was: pyrolysis char of microalgae residue > Al2O3>CaO > K2CO3>MgO > KCl > KOH. The addition of all the catalysts can effectively reduce the potential ecological risk of heavy metals in pyrolysis chars. The addition of KCl, MgO and Al2O3 can increase the content of gasoline components in pyrolysis oil. All the catalysts can reduce the content of CO2 in the pyrolysis gas, and increase the content of CO and hydrocarbon gases. KCl addition showed considerable increase in both yield and quality of pyrolysis oil and gas with a proportion of 5 wt % during microalgae residue pyrolysis.

Pyrolysis characteristics of microalgae (MA) and its chemical extraction residue (MR) were evaluated and compared using a thermal analyzer and a tube furnace reactor. Results showed that the pyrolysis process of MA and MR can be divided into three stages, which corresponded to the volatile of free water, the decomposition of organic compounds and the stabilization of residues, respectively. Due to the removal of lipids after MA extraction, only one weight loss peak was recorded in the second stage of MR. Using the methods of Friedman, FWO and Starink, the average activation energies of MA and MR were calculated as 204.72 and 178.51 kJ/mol, respectively. Pyrolysis oil, gas, and char products were obtained from both MA and MR pyrolysis. Main gas products from pyrolysis of MA and MR contained CO2, CO, H2 and CHs. Compared with MA pyrolysis, the relative contents of CHs were lower (

How to prepare a low-cost carbon material with a high carbon dioxide (CO2) adsorption performance has attracted much attention worldwide. Oil sludge, a hazardous solid waste, needs to be disposed o...

Ta5+ and W6+ co-doped perovskite SrTa0.1W0.1Fe0.8O3-δ (STWF) is studied as a novel cathode material of solid oxide fuel cells (SOFCs). The synergistic effects of Ta/W co-doping on the crystal structure, thermal, electrical and electrochemical properties of STWF were investigated systematically. Ta/W co-doping increased the concentration of oxygen vacancy in STWF, leading to the increase of thermal expansion coefficients (TECs) and electrochemical performance. The average TEC of STWF is 19.8 × 10−6 K−1 during 30–1000°С. At 800 °C, the area specific resistance (ASR) and the maximum power density are 0.074 Ω cm2 and 967 mW cm−2 for STWF cathode based on La0.8Sr0.2Ga0.8Mg0.1O3 (LSGM) electrolyte. The results reveal that high stable valence elements Ta5+ and W6+ co-doped STWF is a good cathode candidate for SOFC.

Nb and W co-doped SrFeO3-δ perovskite SrNb0.1W0.1Fe0.8O3-δ (SNWF) is exploited as a novel cathode for intermediate temperature solid oxide fuel cells (IT-SOFCs). SNWF has a cubic structure with Pm 3 ¯ m space group. Its thermal, electrical and electrochemical properties were examined in detail. Nb/W co-doping increased the oxygen vacancy density of SNWF in comparison with that of Nb and W single-doped SrNb0.2Fe0.8O3-δ (SNF) and SrW0.2Fe0.8O3-δ (SWF) perovskites. Nb/W co-doping resulted in the decrease of electrical conductivity and the enhancement of thermal expansion coefficients (TECs) as well as the electrochemical performance. The average TEC value during 30–1000 °С is 19.6 × 10−6 K−1 for SNWF. At 750 °C, the area specific resistance (ASR) and the maximum power density are 0.113 Ω cm2 and 832 mW cm−2 for the cells based on SNWF electrode and La0.8Sr0.2Ga0.8Mg0.1O3 (LSGM) electrolyte. Good ORR activity and output performance indicate SNWF can be a good alternative cathode material for IT-SOFC.

Layered perovskite oxide LaBa0.5Sr0.25Ca0.25Co2O5+δ (LBSCaCO) is studied as a potential cathode material for intermediate temperature solid oxide fuel cells (IT-SOCFs). Ca-free sample LaBa0.5Sr0.5Co2O5+δ (LBSCO) is also investigated for comparison. The thermal expansion coefficient (TEC) value is reduced from 26.2 × 10−6 K−1 to 20.0 × 10−6 K−1 by Ca doping. The electrical conductivity of LBSCaCO is above 500 S cm−1 from room temperature to 800 °C. Substitution of Sr by Ca can effectively enhance the electrochemical performance. The area specific resistance (ASR) values of LBSCaCO and LBSCO are 0.075 Ω cm2 and 0.084 Ω cm2 at 800 °C, respectively. Moreover, LBSCaCO cathode achieves an excellent outputting of 662 mW cm−2 at 800 °C. Based on these results, Ca doped layered perovskite LBSCaCO can be a cathode candidate material for IT-SOFC application.

Layered perovskite oxides with and without Ca-doped NdBa0.5Sr0.25Ca0.25Co2O5+δ (NBSCaCO) and NdBa0.5Sr0.5Co2O5+δ (NBSCO) are studied to investigate the effects of Ca doping on the crystal structure, thermal behavior, electrical and electrochemical properties. Both NBSCO and NBSCaCO are tetragonal structure with P4/mmm space group. The average thermal expansion coefficient (TEC) value is reduced from 23.3 × 10−6 K−1 to 19.8 × 10−6 K−1 during 30–800 °C. The electrical conductivities are increased by Ca doping. Both electrical conductivities of NBSCO and NBSCaCO are higher than 600 S·cm−1 over 30–800 °C. Substitution of Sr with Ca can effectively improve the electrochemical properties of NBSCaCO. From 650 °C to 800 °C, the area specific resistance (ASR) of NBSCaCO are decreased from 0.62 to 0.062 Ω cm2 and the corresponding output power density are increased from 258 to 812 mW cm−2. On the basis of these results, Ca doped layered perovskite NBSCaCO can be a good cathode candidate material for SOFC application.

From the view point of compatibility of both crystalline and element with the prototypical perovskite-type electrolyte of La0.9Sr0.1Ga0.8Mg0.2O3-δ, a series of micro-Mg-doped La2NiO4+δ compounds with compositions of La2Ni1-xMgxO4+δ (x = 0.0, 0.02, 0.05 and 0.10) were successfully synthesized via a traditional sol-gel process and evaluated as cathode for intermediate-temperature solid oxide fuel cells (IT-SOFC). The effects of Mg-doping on crystal structures, bond properties and covalent states were analyzed by X-Ray Diffraction (XRD), Infrared spectra (IR) and X-ray photoelectron spectroscopy (XPS) techniques, respectively. It is found that Mg-doping is benefit for the migration of the interstitial oxygen by weakening the Ni(Mg) O bond. More importantly, we found that Mg doped at the subsurface under the Ni of (001) surface will promote both the O2 adsorption and decomposition process from the analysis of the oxygen migration dynamics. Considering the balance of electronic conductivity, it was indicated that La2Ni0.98Mg0.02O4+δ (LNM0.02) manifested the optimal electrochemical property with the lowest area specific resistance of 0.05 Ω cm2 at 800 °C, and along with a maximum power density of 528 mW cm−2 for an electrolyte supported single cell LNM0.02|LSGM|NiO-SDC at 800 °C with approximately 20% higher than that of the La2NiO4+δ (LN) (∼429 mW cm−2) cathode. The results indicate that introducing micro-dose of Mg into Ni-site in La2NiO4+δ compound is an efficient way to obtain an excellent cathode material for IT-SOFCs.

Bi-doped La 2- x Bi x Cu 0.5 Mn 1.5 O 6 (LBCM- x , x = 0, 0.1 and 0.2) were synthesized as potential cathode materials for intermediate-temperature solid oxide fuel cells. The effects of 6s 2 lone pair electrons on the electrical and electrochemical properties of LBCMs were investigated. The results reveal that Bi 3+ affects the properties of LBCMs in two ways. First, Bi doping can promotes the formation of oxygen vacancies, which is consistent with the results of first-principles calculations. The formation of oxygen vacancies can increase the amount of Mn 3+ /Mn 4+ pairs for the hopping of electrons and accelerate the oxygen transportation. Second, Bi doping can affect the microstructure of LBCMs and make LBCM-0.1 has the smallest grain size. The dual effects of Bi doping result in the highest electrical conductivity (143.91 Scm −1 ) as well as the lowest polarization resistance (0.101 Ωcm 2 ) of LBCM-0.1 at 850 °C and make it a superior cathode candidate for solid oxide fuel cells.

The Cu/ZnO catalyst prepared by supercritical phase CO2 drying (denoted as CZS catalyst) and the conventional Cu/ZnO catalyst prepared by heating dry process (denoted as CZO catalyst) were comparatively investigated. The low-temperature methanol synthesis reaction from CO + CO2 + H2 using 2-butanol as solvent was conducted over the CZS and CZO catalysts at 443 K and 5.0 MPa for continuous 20 h in a flow-type reactor. It was found that the total carbon conversion of the CZS catalyst was increased from 35.1% to 46.4% and the methanol yield of the CZS catalyst was enhanced from 33.8% to 44.8%, comparing with those of the CZO catalyst. The results of kinetic analysis by in situ diffuse reflectance infrared Fourier transform spectra (DRIFTS) revealed that the reaction rate of the low-temperature methanol synthesis on CZS catalyst was faster than that on CZO catalyst at 443 K, in good accordance to the catalytic reaction performances. It was indicated that the supercritical fluid CO2, which was used to dry the catalyst precursor, suppressed the sintering of the Cu and ZnO particles and increased both the BET surface area of the catalysts and metallic surface area of Cu0, which further improved the reaction activity of the catalyst for the low temperature methanol synthesis.

A series of perovskite oxides have been investigated as excellent potential cathodes for intermediate-temperature solid oxide fuel cells (IT-SOFCs). In this paper, we take the La0.75Sr0.25Cu0.5−xCoxMn0.5O3−δ (LSCCM, x = 0, 0.25 and 0.5) system as subject, with Cu/Mn and/or Co/Mn on B-site and 25% Sr-substituted La ions on A-site, to investigate their structures, thermal stability and electrochemical properties. Pure rhombohedral crystal with space group R 3 ¯ c (no. 167) is identified by Rietveld refinement of X-ray diffraction data (XRD). It is found that the thermal expansion coefficient (TEC) is manageable when Co ion is incorporated, and the low TEC value ranges from 12.7 × 10−6 to 15.4 × 10−6 K−1 that are well compatible with prototypical electrolytes Zr0.84Y0.16O1.92 (YSZ) and Ce0.8Sm0.2O2−δ (SDC). The dc-conductivity is significantly enhanced from 36.5, 90.5 to 173.7 S cm−1 at 850 °C with the increasing Co percent, and accordingly, polarization resistance (Rp) is determined as 0.1291, 0.0835 and 0.0486 Ω cm2 at 800 °C. The high electrical conductivities and low resistances can be attributed to the strong B O bond hybridization and oxygen vacancy formation at elevated temperatures with the introduction of Co ion, which is consistent with the results of first-principles calculation and thermogravimetric analysis. All these results demonstrate that LSCCM series are promising cathodes with controllable TEC for IT-SOFCs.

The effects of Bi-doping and Bi-deficiency of La2ZnMnO6 − δ as cathode on the electrochemical properties were studied through a complex of physical-chemical characterization. We synthesized a series of compounds via a Pechini route, and the phase purity was greatly influenced by the A-site composition. X-ray photoelectron spectroscopy (XPS) testified the state of oxygen species and the mixed-valent states of Bi5 +/Bi3 + and Mn4 +/Mn3 +. The polarization resistances (Rp) of La2ZnMnO6 − δ (LZM), La1.5Bi0.5ZnMnO6 − δ (Bi0.5) and La1.5Bi0.5 − xZnMnO6 − δ (Bi0.5 − x, x = 0.25) are 0.122, 0.102 and 0.076 Ω cm2 at 850 °C, respectively, which are low enough to fulfill the practical application. All the analytical results demonstrate that Bi-substitution on A-sites does promote conductive properties due to the existence of high ionic conductive Bi2O3 phase. In addition, Bi-cation-deficient compound can further improve the transport performance because of the coexistence of Bi2O3 and Bi-cation defects. Therefore, these Bi-doping and Bi-cation-deficiency in LZM compounds can be promising cathode materials for intermediate temperature solid oxide fuel cells (IT-SOFCs).

A series of novel perovskites LaM0.25Mn0.75O3−δ (M = Fe, Co, Ni, Cu) are considered as promising cathode materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs). Polycrystalline powders of LaM0.25Mn0.75O3−δ are synthesized by a modified Pechini method. Powder X-ray Rietveld refinements reveal that LaM0.25Mn0.75O3−δ series are in the orthorhombic perovskite structure within Pnma (no. 62) space group at room temperature. In situ high temperature X-ray diffractions indicate the existence of phase transformation from the orthorhombic Pnma phase to a higher symmetrical rhombohedral phase at elevated temperatures without any second phase formation for all these compounds. Multivalent states of M (Fe, Co, Ni and Cu) and Mn ions are testified by X-ray photoelectron spectroscopy measurement (XPS). The electrical conductivity are measured to be 39.6, 85.3 and 48.1, 99.4 S cm−1 for M = Fe, Co, Ni and Cu, respectively and the corresponding impedance are 0.131, 0.106, 0.107 and 0.0634 Ω cm2 at 850 °C. Among these compounds, LaCu0.25Mn0.75O3−δ exhibits the highest electrical conductivity and the lowest electrode polarization resistances, which is consistent with its calculated smallest band gap and lowest oxygen vacancy formation energy. Moreover, they all exhibit excellent chemical compatibility with prototypical electrolyte Ce0.8Sm0.2O2−δ (SDC). While the overall electrochemical properties of LaM0.25Mn0.75O3−δ (M = Fe, Co, Ni) are high enough to fulfill the practical applications. Thus, these LaM0.25Mn0.75O3−δ (M = Fe, Co, Ni, Cu) compounds are potential cathode materials for IT-SOFCs.

A series of perovskite oxides SrBiMTiO6 (M = Fe, Mn, Cr) have been synthesized and characterized towards application as cathode materials for solid oxide fuel cells (SOFCs). X-ray diffraction (XRD) patterns reveal that all samples are stabilized in $$ \mathrm{Pm}\ \overline{3}\mathrm{m} $$ space group. Electrical conductivity, AC impedance characteristics, and thermal and chemical stability have been studied in order to assess their possible use as SOFC cathode materials. In comparison with other low electrical conductivity cathodes of SOFC, our results suggest that SrBiMnTiO6, which has the highest electrical conductivity (4.02 S cm−1) and moderate polarization resistance (0.104 Ω cm2) at 850 °C, is the most promising candidate among the three perovskite oxides for further study and optimization as a SOFC cathode material.

La2CoMnO6 has attracted intensive research interest because of its prospect for novel technological applications and rich fundamental physics. And, due to the similar radii size as well as small covalent difference (as large as 2) between Co and Mn, cation disorder should be intrinsic within this perovskite. We performed comprehensive first-principles calculations on both La2CoMnO6 (LCMO) and LCMO with CoMn-MnCo antisite defects (AD:LCMO), focusing on the formation of bulk oxygen vacancies, which plays a key role in oxygen ion diffusion process in solid oxide fuel cell (SOFC) electrodes. First, it is found that the covalent states are 2 and +4 for Co and Mn at their regular sites while they are both prone to be +3 in the antisites. The formation energies for oxygen vacancies are predicted to follow the trend Co2+-O-Mn4+ > Co2+-O-Co3+ > Mn3+-O-Mn4+, and the underlying microscopic mechanism is attributed to the more electron delocalization between mixed-covalent transition metals (Co2+-O-Co3+ and Mn3+-O-Mn4+), which is beneficial to diminish the electronic repulsion and help to stabilize the vacancy. Therefore, we could conclude that oxygen ionic conductivity should be enhanced in the compounds with higher degree of cation disorder. Our results indicate that AD:LCMO should be a promising intermediate-temperature solid oxide fuel cell cathode material.

Catalytic reaction performances of home-made mesoporous MnO 2 -supported Fe-based catalyst with copper promoter for Fischer–Tropsch synthesis (FTS) are investigated in a slurry-phase reactor at 533 K–573 K and 1.0 MPa. The present catalyst system exhibits high olefin selectivity, however, the selectivity to ethylene is lower than the extrapolation based on the C 3 + . Simultaneously, the catalyst gives high oxygenates productivity except for the C 1 oxygenates. Comprehensive product distributions including hydrocarbon and oxygenates at different temperatures are presented. Particular attention is paid to the new overall distribution of product based on the carbon numbers when the hydrocarbon is combined with oxygenates. The new distributions at different temperatures show similar trends, displaying low C 1 product selectivity and almost accordant C 2 product selectivity with the extrapolation from Anderson–Schulz–Flory (ASF) law. An attempt is made to elucidate the deviation behavior of C 1 and C 2 hydrocarbon.

A series of the as-burnt and the burnt Cu/ZnO catalysts were prepared by a sol–gel auto-combustion method using metal nitrates with the mole ratio of Cu/Zn = 1/1 (noted as M, M = Cu + Zn) and citric acid (noted as CA). When the xerogels were burnt in the argon atmosphere, H 2 and CH 4 which were came from the decomposition of the citric acid, were the reducing agents and were used in the redox process for synthesizing metallic Cu from Cu 2+ in the chelated compound. The XRD patterns revealed that all the as-burnt catalysts with different M/CA molar ratios were converted into pure Cu and ZnO species. TPR analysis of the as-burnt catalyst illustrated that almost no hydrogen was consumed. It proved that Cu 2+ in the chelated compound was absolutely reduced to metallic Cu in the as-burnt catalyst. The effects of M/CA molar ratio on the properties of catalysts were studied by TG-DTA, FT-IR, Raman spectrum, XRD, SEM-EDS, BET, and N 2 O chemisorption techniques. The activity of the as-burnt catalysts without reduction was investigated for low-temperature methanol synthesis from syngas containing CO 2 using ethanol as a promoter at 443 K and 5.0 MPa for 12 h. The total carbon conversion increased with increasing the content of citric acid and reached a maximum for the as-burnt Cu/ZnO catalyst C 0.8 with M/CA = 1/0.8, and then decreased. The variation trend was in accordance with that of the copper (Cu 0 ) surface area. Comparing with the burnt catalyst C 0.8-air after reduction, the methanol selectivity of the as-burnt Cu/ZnO catalyst was much lower owing to lower hydrogenation activity of the ethyl formate. The as-burnt catalyst C 0.8 was also used in continuous low-temperature methanol synthesis at 443 K and 5.0 MPa for 40 h. The total carbon conversion was stable after 15 h and no obvious deactivation during 40 h reaction, but the methanol selectivity was still not high.

Ethanol was directly synthesized from dimethyl ether (DME) and syngas (CO + H2) with the combination of Cu-modified H-Modernite (H-MOR) zeolite catalyst and metallic Cu/ZnO catalysts in a dual-catalyst bed reactor. The methyl acetate (MA) was firstly formed by DME carbonylation on the upper zeolite catalyst layer, and then was subsequently hydrogenated on the lower Cu/ZnO catalyst layer to be converted into ethanol accompanying with methanol. A copper doped H-MOR catalyst prepared by ion-exchange method exhibited better catalytic activity compared with the pure H-MOR catalyst in the single DME carbonylation reaction, and the influence of reaction temperature was investigated in detail, confirming that the optimal reaction temperature for this copper doped H-MOR catalyst was 493 K. For ethanol synthesis in the dual catalyst bed reactor, the combination of copper doped H-MOR catalyst with Cu/ZnO catalyst effectively improved the DME conversion, enhanced the ethanol selectivity in the final products remarkably, if compared with the combination of pure H-MOR catalyst with Cu/ZnO catalyst.

A copper-based catalyst can be utilized to synthesize methanol from syngas containing carbon dioxide as well as water at low temperature and low pressure. However, the agglomeration of the metallic copper and zinc oxide decreased the catalyst surface area and the Cu-specific surface area. In order to prevent the sintering, the supercritical CO2 was used to extract water from the catalyst precursor. Our results demonstrate that the Cu-specific surface area was the essential factor to affect the catalytic activity. A larger Cu-specific surface area would cause higher methanol synthesis activity. The optimized supercritical CO2 drying condition was at 308 K and 8.0 MPa for 3 h when the methanol yield reached 44.8%.

Bimodal pore Fe–Mn–K catalysts supported onto SiO2 pellet were prepared by a one-step incipient wetness impregnation method. In this method, the active component and promoters were used as the “bricks” to directly build up the small pores inside the large pores of silica gel. The catalysts were applied to catalyze Fischer–Tropsch synthesis in slurry phase. Compared with the SiO2 supported non-bimodal catalysts, the bimodal catalysts exhibited excellent activity due to the improved active metal dispersion and the fastened diffusion efficiency. The preparation method was much more feasible than the previous two-step method, and can be extended to prepare bimodal catalysts with different active components. Bimodal pore Fe–Mn–K catalysts were prepared by a one-step incipient wetness impregnation method using the active component and promoters as the “bricks” to directly build up the small pores inside the large pores of silica gel. The prepared catalyst exhibited excellent activity in slurry phase Fischer–Tropsch synthesis.

A core–shell-like encapsulated catalyst was designed where Pd–Co/activated carbon (A.C.) catalyst was enwrapped by silicalite-1 zeolite membrane, which greatly improved normal to iso ratio of aldehyde products during hydroformylation of 1-hexene with syngas (CO + H2), due to its spatial confined structure and shape selective property derived from zeolite membrane.

Low temperature methanol synthesis is a promising technique for the practical methanol industry. New developments of a new kind of low temperature methanol synthesis were reviewed, including the effects of feed gas, reaction solvent, supercritical media and catalyst modification. The reaction mechanism and kinetics were also summarized primarily. Carbon dioxide played an important role in this new kind of low temperature methanol synthesis. It reacted with hydrogen adsorbed on catalyst surface to form HCOOM, an important reaction intermediate. Alcohol solvent in the low temperature methanol synthesis performed not only a media, but also a homogeneous catalyst. The reaction of the adsorbed formate species with alcohol on Cu/ZnO catalyst surface proceeded according to the Rideal mechanism rather than Langmuir–Hinshelwood mechanism to form alkyl formate. The formation of alkyl formate from alcohol solvent and hydrogenation of such an alkyl formate were the key steps in low temperature methanol synthesis reaction. These results provided new insights into low temperature methanol synthesis.